Currently, parents' interest in preventing children from going missing is increasing, and various products and services for preventing children from going missing are being developed to satisfy parents' demand. In a mobile communication network, location-tracking service is one of the services for preventing children from going missing. The location tracking service is a service that detects the location of a mobile terminal in a child's possession and informs his or her guardian of the location of the child's mobile terminal.
The location-tracking service uses known technologies that detect the locations of mobile terminals. Currently well-known technologies for detecting the locations of mobile terminals are generally classified into Global Positioning System (GPS) based positioning schemes and base station based positioning schemes.
The base station based positioning schemes are sub-divided into a scheme that uses the cell identifier of a base station communicating with mobile terminals, and a scheme that performs estimation using approximate distances from three base stations that are capable of receiving signals from mobile terminals.
Meanwhile, the GPS-based positioning schemes are schemes that transmit location information, which is received by a GPS receiver installed in a mobile terminal, to a server through the mobile terminal. That is, the GPS receiver determines current location information and time information by processing signals received from man-made satellites, and provides the determined location and time information to a server through the mobile terminal. A GPS is a system that is configured to determine location in three dimensions, which are composed of latitude, longitude and altitude, and time deviation using man-made satellites.
Although the conventional location tracking service can be usefully used when children have gone missing, it is of little use in the case in which a guardian desires to monitor children playing or studying in a specific zone. That is, in the case of using a conventional location tracking service, the guardian must monitor a ward's location at all times. Furthermore, in the case in which the ward moves out of the specific zone while the guardian neglects to monitor the child, it may be too late for the guardian to react to the movement because the guardian is not promptly made aware of it.
Meanwhile, Korean Laid-open Patent Application No. 2003-71267 proposes technology that sets a specific zone as a safety zone, and tracks the location of the ward's mobile terminal, and informs a guardian that a ward has moved out of the specific zone when the ward moves out of a safety zone.
However, the Korean Laid-open Patent Application No. 2003-71267 conceptually described only methods of setting a safety zone, and checking whether the ward's mobile terminal has moved out of the safety zone, but failed to propose concrete methods to achieve the object.